1. Field of the Invention
The present invention concerns the technical area of fabricating preforms or multidirectional fibrous reinforcements designed for fabricating parts made of composite materials.
2. Description of Related Art
In that technical area it is known, specifically from patent application FR 2 581 379, starting with reinforcing threads, how to make a preform or multidirectional fibrous reinforcement designed to be resin-injected and become a part made of a composite material.
Patent application FR 2 581 379 proposed to make preforms for truncated conic or ellipsoid revolving parts, such as jet engine vents, by winding a reinforcing thread that has been pre-impregnated with a binding agent, on a support having teeth, designed to avoid any relative slippage of the thread on the support, so as to preserve a perfectly even distribution of the reinforcing thread on the fibrous reinforcement.
Using such a fabrication procedure, it is possible to make spoolable multidirectional fibrous reinforcements that are rotationally symmetrical. However, this fabrication process has the disadvantage of not permitting the fabrication of multidirectional fibrous reinforcements having complex or awkward forms, with no favored axis of rotational symmetry or, again, having locally concave areas, with regard to the general form of the fibrous reinforcement.
In addition, the process according to patent application FR 2 581 379 has the disadvantage of placing the reinforcing thread, while it is being laid down, in a state that could be described as a pre-constraint or pre-stressed. The pre-constraint influences the mechanical behavior of the multidirectional fibrous reinforcement and can affect the performance of the part incorporating the fibrous reinforcement.
Also, because of the tension applied to the reinforcing thread, winding it requires a deposit path that necessarily corresponds geodesically to the support surface and thus limits the types of reinforcing structures that can be made.
Thus arises the need to have a new fabrication process available that permits preforms or multidirectional fibrous reinforcements to be made that can have complex or awkward forms, specifically with locally concave areas and specifically in these areas having reinforcing threads arranged in different directions.